Polypropylene and Polycarbonate containers have a varied effect on coagulation after haemodilution, as judged by TEG® in vitro

The reasons for this study were multi-factorial, but mostly due to some interesting data obtained from a pilot study conducted at University College London (UCL). In that study, the coagulation effects in vitro of two hetastarch solutions were compared with two crystalloids by means of thrombelastography (TEG®). The fluids compared were: 1. Hespan® (HES), a high molecular weight hetastarch (450kDa/O.7 substitution ratio) in a 0.9% saline solution - Laevosan, Austria. 2. Hextend® (HEX), also a high molecular weight hetastarch (670/0.75 substitution ratio) in a balanced electrolyte, lactate and glucose solution - BioTime Inc, Berkeley, California, USA. 3. Saline 0.9% 4. Hartmann's Solution (Ringer's Lactate) The crystalloids revealed no surprising differences known from previous published data, but data obtained from the hetastarch solutions revealed contradictory results to known in vivo results found in a phase III trial. This previous Phase III in vivo trial showed that HEX haemodilution produced a superior coagulation profile to HES, along with a significantly shorter r-time than HES. There was also a significantly smaller transfused volume of blood than HES in the HEX-treated patients. This Phase III study prompted the initial UCL in vitro haemodilution study mentioned above. In the UCL study, there were significantly impaired TEG® results, indicating severe hypocoagulability with HEX, when compared with HES. This included prolonged r-and k-times, as well as reduced a-angles and maximum amplitudes in the HEX group, compared with HES and crystalloid groups. Many theories were discussed for these controversial UCL results, but the thought was that a container-effect could have been responsible, as the in vitro UCL study methodology included the use of a polycarbonate container for initial storage, as well as for haemodilution of the blood in vitro. In view of the known wettable surface, as well as a strong negative surface charge of polycarbonate, it was suggested that the container surface itself could have affected coagulation. When different ionic compositions of the various fluids and starches were taken into account, it seemed possible that some interaction between the fluids and the material of the containers could have induced or inhibited coagulation at the container surface. The suspicion was that the observed change in TEG® variables was likely due to a methodologic idiosyncrasy. Previous track record of haemodilution and TEG research at the University of Cape Town made it an obvious setting for exploration of this problem. Preparations were thus made to test container effects with haemodilution in vitro at Prof MFM James' anaesthesia laboratory at the University of Cape Town. The hypothesis was that the use of polypropylene and polycarbonate containers, with their different chemical and surface properties, would lead to a variability in TEG® results obtained from fresh whole blood, as well as blood diluted with various fluid solutions. Choosing TEG® as a monitor of coagulation was essential, as it has a well-established track record in monitoring coagulation effects in trials of haemodilution (in vitro and in vivo). TEG® produces reliable and quick results, giving a reflection of global coagulation function. It, along with the Sonoclot®, are the only two devices which can reliably diagnose a hypercoagulable state. More will be mentioned on the TEG® later

Symmetric presentations of finite groups

Symmetric presentations of groups allow us to represent, and manipulate, group elements in a manner that is typically more convenient than conventional techniques; in this sense, symmetric presentations are particularly useful in the study of large finite groups

Nurse–patient ratios and infection control practices:A cross-sectional study

Background: Substantial research evidence supports the link between nurse staffing and patient outcomes. Low nurse staffing and high workloads have been linked to poor hand hygiene, ineffective equipment cleaning, and incorrect use of personal protective equipment (PPE), with potential outcomes of intravenous cannula infections, wound infections, urinary tract infections, and pneumonia. Research is limited regarding the impact of staffing models on specific infection control practices (ICP) such as wound dressing, oral hygiene, or patient education. Aim: To describe nurses’ perceptions of the impact of nurse–patient ratios on ICP. Methods: A cross-sectional survey using a questionnaire with items drawn from pertinent research was distributed via QR code. Data were collected from 51 nurses on 12 units in a large tertiary referral hospital where a minimum 1:4 patient ratio had been recently introduced. Analysis was comparative and descriptive. Findings: Most participants were female registered nurses with less than 10 years’ experience in nursing. More than half had experienced a 1:4 ratio on their most recent shift. Nurses in this group indicated that they could complete infection control care in a timely manner, were more likely to provide infection control-related patient education, and had more time to communicate with the treating team about infection control matters. Hand hygiene and the use of PPE were not associated with the 1:4 staffing model. Discussion: ICP included patient education, effective communication, and support appears to be strengthened by ratio staffing. These actions, together with more timely completion of activities such as oral hygiene and wound dressings, may significantly impact hospital-acquired infections and enhance patient safety. Conclusion: ICP may be strengthened by staffing consistent with the 1:4 ratio framework. This suggests that ratio-based staffing can have an early and important impact on practice. Findings regarding foundational practices, teamwork, and team support warrant further investigation.</p

Goal-directed or goal-misdirected - how should we interpret the literature?

Goal-directed therapy (GDT) can be a vague term, meaning different things to different people and, depending on the clinical environment, sometimes even different things to the same person. It can refer to perioperative fluid management, clinicians driving oxygen delivery to supramaximal values, early treatment of sepsis in the emergency department, and even to restriction of perioperative crystalloids with the goal of maintaining preadmission body weight. Understandably, strong opinions about GDT vary; some clinicians consider it essential for perioperative care, others completely ineffective in critically ill patients. This commentary aims to further position the excellent review by Lees and colleagues in the context of the critical care and perioperative setting

A Function Acquisition Speed Test for Equivalence Relations.

The current study employed a stimulus equivalence paradigm to assess the ability of the recently developed Function Acquisition Speed Test (FAST) to measure the existence and strength of experimentally produced derived relations. Twenty-two participants were exposed to a One-to-Many stimulus equivalence training procedure (A1–B1, A1–C1, A2–B2, A2–C2), followed by testing for derived B1–C1 and B2–C2 relations. All participants were then exposed to a FAST procedure in which a simple common operant response was established for pairs of equivalent stimuli (e.g., B1 and C1) in one block of training. In another bock of training, a common response was established for pairs of non-equivalent stimuli (e.g., B1 and C2). Trial numbers required for participants to reach mastery criteria differed across the two FAST blocks, as expected, but only for those participants who had passed the prior equivalence testing phase. This finding suggest that the FAST procedure functions as both a concurrent measure of stimulus equivalence class emergence and a functional-analytic tool that might assess unreinforced and socially sensitive stimulus relations formed in the world outside the laboratory. Large inter- and intra-participant variations in performances across FAST blocks are discussed